摘要
It is complicated to model the acoustic field in stratified ocean for airborne aircraft,due to high speed of the source and air-to-water sound transmission.To our knowledge,there are very few papers in the open literature dealing with this complicated problem;but,in our opinion,they all require great amount of computation.We now propose a different method that requires much less computation.We improve the wavenumber integration method to model the received temporal signal for a moving source in stratified ocean and sum up in a concise form the core of our paper as follows:(A) Eq.(11) can be calculated by means of fast Chirp Z transform and the signals at all N time points are generated simultaneously;(B) direct numerical evaluation of the wavenumber integral in Eq.(4) produces large numerical errors;so it is necessary to shift the integration slightly below the real axis;(C) we compare the computation cost of direct calculation method with that of our fast calculation method;from the results presented in table 1,we can see that the fast calculation method consumes much less computation time,particularly for long duration signals;(D) for an airborne rapidly moving source,we compute the Doppler-shifted signals in shallow water and analyze their short-time Fourier transform;from Fig.1b,we can see that the received signals have multiple frequency components for a tonal source due to source motion and that each component corresponds to an arrival path.
It is complicated to model the acoustic field in stratified ocean for airborne aircraft, due to high speed of the source and air-to-water sound transmission. To our knowledge, there are very few papers in the open literature dealing with this complicated problem~ but, in our opinion, they all require great amount of computation. We now propose a different method that requires much less computation. We improve the wavenumber integration method to model the received temporal signal for a moving source in stratified ocean and sum up in a concise form the core of our paper as follows ： （A） Eq. （11） can be calculated by means of fast Chirp Z transform and the signals at all N time points are generated simultaneously; （B） direct numerical evaluation of the wavenumber integral in Eq. （4） produces large numerical errors; so it is necessary to shift the integration slightly below the real axis; （C） we compare the computation cost of direct calculation method with that of our fast calculation method ; from the results presented in table 1, we can see that the fast calculation method consumes much less computation time, particularly for long duration signals; （D） for an airborne rapidly moving source, we compute the Dopplershifted signals in shallow water and analyze their short-time Fourier transform; from Fig. 1b, we can see that the received signals have multiple frequency components for a tonal source due to source motion and that each component corresponds to an arrival path.
出处
《西北工业大学学报》
EI
CAS
CSCD
北大核心
2007年第6期855-859,共5页
Journal of Northwestern Polytechnical University
关键词
水下声学
空气-水声传播
快速移动资源
波数整合
wavenumber integration, air-to-water sound transmission, rapidly moving source
作者简介
Zhang Yipeng（1979-）, Ph. D of Northwestern Polytechnical University, main research field; underwater acoustic modeling and acoustic signal processing
